In many ink jet systems, ink is supplied to a chamber or passage connected to a nozzle from which the ink is ejected drop-by-drop as a result of successive cycles of decreased and increased pressure applied to the ink in the passage. The pressure cycles can be generated by a piezoelectric crystal, a heater, or a Micro Mechanical Device. If the ink introduced into the passage contains dissolved air, decompression of the ink during the reduced pressure portions of the pressure cycle may cause the dissolved air to form small bubbles in the ink within the passage. Repeated decompression of the ink in the chamber causes these bubbles to grow and such bubbles can produce malfunctions of the ink jet apparatus. Degassing of ink typically utilizes a semi-permeable membrane that is in contact with the ink on one face of the membrane. Reduced pressure is applied to the other side of the membrane to extract dissolved air from the ink in the ink path.